Shoulder joint
The glenohumeral joint is a multi-axial synovial joint between the hemispheric humeral head articulates with shallow pear-shaped glenoid fossa. The joint is surrounded by synovial lined fibrous capsule and strengthened with ligaments. Movement: * Flexion: Pectoralis major, deltoid, coracobrachialis & biceps muscles * Extension: Deltoid & teres major muscles ** If against resistance, also latissimus dorsi & pectoralis major * Abduction: Deltoid & supraspinatus muscles ** Subscapularis, infraspinatus & teres minor exert downward traction ** Supraspinatus contribution controversial * Medial rotation: Pectoralis major, deltoid, latissimus dorsi & teres major muscles ** Subscapularis when arm at side * Lateral rotation: Infraspinatus, deltoid & teres minor muscles Relations: * superiorly: supraspinatus, deltoid * inferioly: long head of triceps and axillary nerve/circumflex vessels * anteriorly: subscapularis, short head of biceps * posteriorly: infraspinatus and teres minor Joint capsule * margin of the glenoid fossa to anatomical neck of the humerus, with insertion of biceps tendon. * reinforced by the rotator cuff, ligaments, labrum and the coracoacromial arch superiorly. It has the weakest support inferiorly. Rotator cuff * Supraspinatus, infraspinatus, subscapularis & teres minor * Tendons interdigitate forming a continuous band at attachment to humerus * Origins ** Supraspinatus: Supraspinatus fossa of scapula ** Infraspinatus: Infraspinatus fossa of scapula ** Teres minor: Lateral scapular border, middle ** Subscapularis: Anterior scapular surface * Insertions ** Supraspinatus, infraspinatus & teres minor insert on the greater tuberosity ** Subscapularis inserts on the lesser tuberosity Ligaments * Coracoacromial ligament ** Anterior 2/3 of coracoid to tip of acromion * Coracoclavicular ligament ** Base of coracoid process to clavicle ** Stabilizes acromioclavicular joint ** Conoid & trapezoid portions merge to form a V * Coracohumeral ligament ** Lateral base of coracoid to lesser & greater tuberosities ** Blends with subscapularis tendon, supraspinatus tendon, joint capsule & superior glenohumeral ligament * Superior & inferior acromioclavicular ligaments * Superior, middle & inferior glenohumeral ligaments ** Superior and middle glenohumeral ligaments extend from superior glenoid region to lesser tuberosity ** Inferior glenohumeral ligament (anterior band, posterior band & axillary pouch) extends from inferior labrum to humeral anatomic neck Bursae: there are many bursae associated with the shoulder but two in particular have clinical significance 1: * subacromial bursa * subscapular bursa -between subscapularis tendon and glenoid neck; communicates with the joint cavity via the foramen of Weitbrecht Arterial supply: anastomosis around the shoulder with principal contributions from: * Anterior Circumflex Humeral Artery: Runs deep to coracobrachialis and biceps muscle. Passes around the surgical neck of the humerus. Anastomoses with the posterior circumflex humeral artery * Posterior Circumflex Humeral Artery: Runs through the quadrangular space between subscapularis and teres major. Lateral to the triceps and medial to the humerus. Encircles the posterior aspect of the humerus and anastomoses with the deep brachial artery * Suprascapular artery from the thyrocervical trunk (subclavian artery): Passes inferior and laterally across the scalenus anterior and phrenic nerve.Runs laterally under the clavicle. Arrives at the scapular notch, passes around it above the superior transverse ligament of the scapula and reaches the supraspinous fossa of the scapula. Supplies the supraspinatus, and crosses the spine to supply the infraspinatus muscle. Venous drainage: Follows the arteries above and drain into the cephalic and the axillary veins Nerve supply: Articular branches of the: * Axillary nerve - inferior capsule * Lateral pectoral nerve - anterosuperior capsule * Suprascapular nerve - posterosuperior capsule * Musculocutaneous nerve (Last only) Normal variant: * Buford complex – deficiency in anterosuperior labrum and thickening middle glenohumeral ligament * Sublabral foramen – separation of the labrum from the underlying glenoid. * Sublabral recess present at the attachment of the biceps tendon to the glenoid labrum. * Benign glenoid cartilage defect * Tubercle of Ossaki * Rotator cuff insertion, i.e. supraspinatus into bicipital groove.